Can you name some of them?
Harrison Consoles paid Paul Davis and use ardour in at least some of their
consoles. And these consoles are targeted primarily at the film industry afaik.
SAE is using ardour in their studios (probably not exclusively).
The Studio of Ron Parker (don't remember the website) uses ardour for
commercial music production since years.
Several keyboard manufacturers have built keyboards running on linux using
open source software. (Because some of them don't advertise this, LS has the
license it has.)
You need more?
You don't name much pro studio's for recording/mixing/mastering
Yes I need more ;)